Golf ball cover



Patented June 14, 1938 4 I UNI TED STATES PATENT 'OFFI CE GOLF BALL COVER James A. Merrill, Akron, Ohio, assignor to Wingioot Corporation, Wilmington, D'el., a corporation of Delaware N o Drawing. Application November 4, 1933, Serial No. 696,689

3 Claims. -(Cl. 27362) This invention relates to golf ball covers. 'It added in sufiicient quantity to stop any further includes golf balls to which the new covering reaction. One-half pound of water per pound material has been applied and the method of of chlorostannic acid used is satisfactory for this making such golf balls, purpose.

According to this invention a golf ball center The reaction product is then added to some- 5 which may be prepared in any usualway is what more than its own volume of water, for excovered with a composition which includes a therample, 2 gallons of water per gallon of reacted moplastic rubber derivative and the composition cement. The emulsion thus formed is steamis applied to the golf ball center by molding under distilled with agitation to remove the solvent, and pressure with heating. The thermoplastic rubthe reaction product, which is a condensation 10 her derivative used in the golf ball cover has less derivative of rubber, is precipitated as a lightchemical unsaturation than rubber itself and is colored, finely divided material. This is centritherefore referred to as a derivative having a fuged and dried in a vacuum.

(CsHs): structure in which more carbon atoms A suitable product may also be obtained from are directly connected than in rubber. It may dead milled pale crepe rubber, that is, rubber 15 be a hydrocarbon having the empiricalformula with a plasticity of around 100-115. A 12% solu- (CsHa): although rubber derivatives containing tion of such dead milled rubber in benzene is other elements may be employed and for various reacted with 10% of crystalline chlorostannic reasons. These are all condensation derivatives acid and the product thus obtained steam-disof rubber. A chlorine-containing rubber derivatilled and precipitated in water. The reaction of 2 tive which is apparently a hydrogen chloride the chlorostannic acid on the rubber is terminated addition product with a (CsHs): nucleus is prewhen the intermediate product thus obtained f red. yields on quenching in water a final product with.

The thermoplastic rubber derivatives are rea hardness of 83-84 at C. 25 silient and when mixed with a rubber-like mate- The golf ball covering material is made from 25 rial, form a cover which is not easily cut and will such a chlorine-containing thermoplastic derivawithstand the shock of the impact of the golf tive in the following way. 10 parts of titanium 1 club on the ball and furthermore, such covers oxide and 60 parts of the chlorine-containing have a good surface which is hard and smooth. rubber derivative are mixed together on a rubber Be u ta p r ha and plasticizers and filling mill preferably heated to around IOU-120 F. 40 30 material, etc. may be added to the covering comparts of pale crepe rubber are added to this mixposition. The covering may be vulcanized altureon the mill a little at a time. A very small though an unvulcanized covering is very satis quantity of rubber is first added and the remaintory- In generaLit is desirable to applya, der is then added in slightly increasing amounts.

surface coating of paint to the cover as is usual If too much rubber is added at the beginning th 35 in the manufacture of golf balls. product-tends to crumble and cannot be milled A chlorine-containing rubber derivative which satisfactorily.

has given very satisfactory results may b pre- The composition may be formed into hemipared in the following way. Pale crepe rubber is phe a up i a hot m l in a temperature 40 lnilled until it has a plasticity of about 300 as of t F-, th n l d d tw u t us 40' measured by a Williams plastometer, A sumcieni; formed plac d around a suitable golf ball center amount of this plasticized rubber is dissolved in and molded in Place at a temperature of about benzene to make a 10% cement. To this cement 150 using Pressure o 1 p there is added 10% of crystalline hydrated chloro- The ps are molded a an elevated temperature 5 stannic acid based on theweight of the rubber. to i u th r re a n ng the r hap until 41- 45 The solution is heatedito boiling under a reflux plied t th f a t he l formed condenser and the heatingcontinued until a prodin is W y a g life, ve a d distance not is obtained which on decomposition in water W en properly hit and the cover is not easily will give a product with a'hardness of 83-84 at damagedv p 25 C. as measured by a Shore hard rubber .Instead of forming the'material into cups it 50 durometer. The reaction of the chlorostannic may be calendered to desired thickness, cut into acid on the rubber is advantageously controlled discs about 2 inches in diameter andthe discs by sampling andfitermining the viscosity of the heated'until they become soft. The softened discs samples. When the reaction has proceeded to are fitted into the two halvesof the mold and then 5 the desired point "water or sodium hydroxide is molded around the center. v

If a vulcanized cover is desired it may be obtained by adding to the above formula 1 part of sulfur, 1 part of mercaptobenzothiazole, 0.5 part of tetra methyl thiuram disulflde and 5 parts of zinc oxide. The vulcanizing ingredients are advantageously milled into the composition on a rubber mill and the curing may takeplace at 250-270 F. and is preferably carried out at about 260 F.

It has been found that if balata is added to the thermoplastic rubber derivative and rubber it is not necessary to regulate the chlorostannic acid reaction to produce a product of the hardness specified above. A somewhat harder or softer material may be used and more or less rubber may be combined with it. However, a rubber derivative of about the hardness specified is preferred. For example, about equal parts of rubber and the rubber derivative may be used. Formulae which have given satisfactory results include the following:

Formula I Parts Deresinated balata 36 Rubber derivative 29 Pale crepe rubber 26 Titanium oxide 9 Formula II Parts Deresinated balata 35 Rubber derivative 65 Pale crepe rubber 35 Titanium oxide 10 Formula III Parts Deresinated balata 35 Rubber derivative '70 Pale crepe rubber Titanium oxide 10 Formula IV Parts Deresinated balata Rubber derivative 60 Pale crepe rubber '40 Titanium oxide 10 The titanium oxide is used to give a lightcolored product. Other pigments may be employed for this purpose.

Cups may be made -from any of the above formulae in either a hot or a cold mold and the cups thus formed molded onto a suitable golf ball center. Covers may also be made of discs made from the above mixtures.

Covers of this type may be vulcanized by adding 1 part of sulfur, 5 parts of zinc oxide and a suitable accelerator, such as 1 part of mercaptobenzothiazole and 0.5 part of tetra methyl thiuram disulfide. These ingredients are advantageously incorporated with the com osition on a rubber mill. In compounding it is p eferred to first add the rubber to the rubber derivative and then add the balata. The rubber isadvantageously added in small increments. The vulcanizing materials may then be added. According to another method of mixing, the vulcanizing materials are added to a small amount of the rubber. This mixture is added to the balance of the rubber, balata and rubber derivative after they have been milled together.

Instead of employing chlorostannic acid to produce the chlorine-containing rubber derivative described above, tin tetra chloride may be used in the presence of hydrochloric acid as by adding an aqueous hydrochloric acid solution to the mixture. Instead of tin tetra chloride, chromic chloride and other halides of amphoteric metals may be employed with hydrochloric acid to form a chlorinecontaining rubber derivative. Ferric chloride and other compounds which produce dark-colored products may be used altho the lighter-colored products give a better appearing ball.

A rubber derivative which does not contain combined chlorine may be used in forming the golf ball covers. For example, a suitable derivative is one formed by reacting a benzene cement with tin tetra chloride, quenching the reaction mixture in a large volume of water and then removing the solvent by steam distillation. The reaction of the tin tetra chloride is so controlled as to produce'a final product of the desired hardness. If the rubber derivative is to be used withrubber alone with possibly the addition of inert.

fillers, such as titanium oxide, the reaction is controlled so as to produce a product with a hardness of 83-84 at 25 C. Rubber may be mixed with this product as with the chlorinecontaining product to produce a golf ball cover. Balata, etc. may also be added with a rubber derivative of this type. Sulfur may be added to any such mixture and the cover vulcanized if desired.

, Rubber derivatives similarly produced by the reaction of other halides of amphoteric metals and rubber, such as chromic chloride, aluminum chloride, ferric chloride, etc. with subsequent quenching may likewise be used with rubber-like materials to make the golf ball covers of this invention.

These covers are tough and durable. The balls give good distance when properly hit and have long life. It is intended that the application shall cover by suitable expression in the appended claims whatever features of patentable novelty reside in the invention. In the claims rubberlike material means rubber, balata. gutta percha or an equivalent material.

What I claim is:

1. A golf ball which comprises a center and a cover molded on the center which cover is composed substantially entirely of an admixture of at least one rubber-like material and a thermoplastic rubber derivative with a Shore hardness in the eighties, which rubber derivative is obtainable by treating with water the reaction product of rubber and the halide of an amphoteric metal or chlorostannic acid, said cover being not easily out due to the fact that the weight of the rubber derivative is equal to between32 and 60% of the combined weight of the rubber derivative and rubber-like material present in the cover.

2. A golf ball having a cover as in claim 1, said cover comprising as rubber-like materials, substantial amounts of both rubber and balata.

3. A golf ball having a cover as in claim 1, said cover being vulcanized.

JAMES A. MERRILL. 

